Watch Korean films and cartoons. Get your hands on some Korean DVDs (with subtitles) or watch Korean cartoons online. This is an easy, entertaining way to get a feel for the sound and structure of the Korean language.
If you're feeling particularly proactive, try pausing the video after a simple sentence and repeat what has just been said. This will lend your Korean accent an air of authenticity!
If you can't find any Korean films to buy, try renting them from a movie rental store, which often have foreign language sections. Alternatively, see if your local library has any Korean films or ask if they would be able to source some for you.
